NW 102/MSD/60lb injector questions
02-24-2016, 06:09 PM
#1
NW 102/MSD/60lb injector questions
I am doing my final upgrade to my '08 Z06. As far as power mods, it currently has ARH 1 7/8" long tubes and X pipe, halltech 103, 235/251 .657/.666 115 cam, decked heads (~12:1), and a ported stock throttle body. Tuned, making approximately 550 RWHP.
I am adding a NW 102 throttle body, MSD intake manifold, and 60 lb injectors. I plan to do the work myself since it's all really basic stuff. My issue is that I will probably have to drive over 100 miles to make it to a reputable tuner.
I know that the 102mm and MSD intake combo will probably give it bad manners without a tune change, and will almost certainly run me out of fuel on the top end of the throttle if I were silly enough to push it. I plan to staying out of the gas on the way to a tuner, regardless, and I expect that keeping the throttle well <50% should not cause any real issues with these changes alone.
The injectors are what I am concerned about. If I do a one shot install, which would make more sense and be much easier, I'll be going from 42 lb injectors to 60 lb injectors on the 42 lb tune. WOT tune is not a concern since I'm going to be staying out of the gas. By my calculations (simple linear extrapolation of fuel delivery), I expect that idle and cruising AFR will go from the 14.7:1 range down to ~10.3:1.
To the best of my understanding, although I should expect complete garbage gas mileage, I should not have any issues with plug fouling on the highway in this range. So, guys with experience here... what should I expect? Is my math right? Do you see a significant plug fouling risk here? Is there anything that I'm overlooking that makes this a bigger no-no than I'm thinking?
Thanks.
I am adding a NW 102 throttle body, MSD intake manifold, and 60 lb injectors. I plan to do the work myself since it's all really basic stuff. My issue is that I will probably have to drive over 100 miles to make it to a reputable tuner.
I know that the 102mm and MSD intake combo will probably give it bad manners without a tune change, and will almost certainly run me out of fuel on the top end of the throttle if I were silly enough to push it. I plan to staying out of the gas on the way to a tuner, regardless, and I expect that keeping the throttle well <50% should not cause any real issues with these changes alone.
The injectors are what I am concerned about. If I do a one shot install, which would make more sense and be much easier, I'll be going from 42 lb injectors to 60 lb injectors on the 42 lb tune. WOT tune is not a concern since I'm going to be staying out of the gas. By my calculations (simple linear extrapolation of fuel delivery), I expect that idle and cruising AFR will go from the 14.7:1 range down to ~10.3:1.
To the best of my understanding, although I should expect complete garbage gas mileage, I should not have any issues with plug fouling on the highway in this range. So, guys with experience here... what should I expect? Is my math right? Do you see a significant plug fouling risk here? Is there anything that I'm overlooking that makes this a bigger no-no than I'm thinking?
Thanks.
02-25-2016, 04:15 PM
#3
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St. Jude Donor '15
It will depend on your current tune. Fuel trims can make 30+% adjustments to fueling based on O2 sensor readings. The ECM will try to get you back to 14.7:1 as long as it's within the level of change it's allowed to make (and assuming the current tune is closed loop).
I had an O2 sensor go out a few weeks ago and was at something stupid like +56% fuel trims because it just kept trying to add more fuel to get the O2 sensor reading to go rich and it never did
My point being.. if you can get it to start and run long enough for the O2 sensor / fuel trims to become active then you might be fine. Obviously stay away from WOT as fuel trims don't work there.
Worst case I'd just change the injectors when you get to the tuner if it won't start.
The bigger TB may make things more complicated but it's still worth trying. I mean, even if you had to install the TB in the parking lot that's not exactly a big deal.
I had an O2 sensor go out a few weeks ago and was at something stupid like +56% fuel trims because it just kept trying to add more fuel to get the O2 sensor reading to go rich and it never did
My point being.. if you can get it to start and run long enough for the O2 sensor / fuel trims to become active then you might be fine. Obviously stay away from WOT as fuel trims don't work there.
Worst case I'd just change the injectors when you get to the tuner if it won't start.
The bigger TB may make things more complicated but it's still worth trying. I mean, even if you had to install the TB in the parking lot that's not exactly a big deal.
Last edited by schpenxel; 02-25-2016 at 04:16 PM.
02-25-2016, 08:44 PM
#4
It will depend on your current tune. Fuel trims can make 30+% adjustments to fueling based on O2 sensor readings. The ECM will try to get you back to 14.7:1 as long as it's within the level of change it's allowed to make (and assuming the current tune is closed loop).
I had an O2 sensor go out a few weeks ago and was at something stupid like +56% fuel trims because it just kept trying to add more fuel to get the O2 sensor reading to go rich and it never did
My point being.. if you can get it to start and run long enough for the O2 sensor / fuel trims to become active then you might be fine. Obviously stay away from WOT as fuel trims don't work there.
Worst case I'd just change the injectors when you get to the tuner if it won't start.
The bigger TB may make things more complicated but it's still worth trying. I mean, even if you had to install the TB in the parking lot that's not exactly a big deal.
I had an O2 sensor go out a few weeks ago and was at something stupid like +56% fuel trims because it just kept trying to add more fuel to get the O2 sensor reading to go rich and it never did
My point being.. if you can get it to start and run long enough for the O2 sensor / fuel trims to become active then you might be fine. Obviously stay away from WOT as fuel trims don't work there.
Worst case I'd just change the injectors when you get to the tuner if it won't start.
The bigger TB may make things more complicated but it's still worth trying. I mean, even if you had to install the TB in the parking lot that's not exactly a big deal.